Size for wood-fiber products



. No Drawing.

UNITED STATES PATENT OFFICE.

BENJAMIN WILSON SIDWELL, 0F BUFFALO, NEW YORK, ASSIGNOR TO THE BEAVER COMPANY, A CORPORATION OF OHIO.

SIZE FOR WOOD-FIBER PRODUCTS.

To all whom it may concern:

Be it known that I, BENJAMIN WILSON SIDWELL, residing at Buffalo, in the county of Erie, State of New York, have invented certain new and useful Improvements in Size for'lVood-Fiber Products; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present inventionrelates to a size suitable for use on articles formed from wood fiber, wood pulp, or the like, such, for instance, as wall board.

Wall board may be made from wood fiber or wood pulp, either ground wood pulp, waste paper or cooked pulp, used alone or intermixed, and ordinarily is marketed in substantially rigid sheets. The wall board may consist of a single layer of material or of a plurality of plies pasted or cemented together. Generally it is used as a building material by nailing or tacking it directly to the studding of a room, so that it may serve in place of lath and nlaster as the inner wall of the room, being usually ornamented with paint, or the like, as desired.

Wall board, as manufactured, contains a .certain percentage of moisture and also has the characteristic of changing in its moisture content in accordance with the humidity of the surrounding air; these changes ordinarily being slow but nevertheless appreciable. Such changes in moisture content are sometimes very troublesome in new buildings where the moisture initially present in the lumber, particularly green lumber, gradually works through into the wall board, causing expansion and sometimes warping and buckling. The characteristic of wall board to absorb moisture extends also to paints, stains and similar decorative liquids, and if not counteracted leads to exccs'si've waste of the decorative agent, as well as to unsatisfactory effects.

The absorption of moisture and paint by wall board can be reduced by surface sizing. Thus, it has heretofore been customary to surface size wall board by applying a solution of gums, resins, and other materials. Most sizing compounds are essentially-resins, gums, or similar substances, treated for various purposes, and cut in some suitable solvent or solvents. \The function of the sol- Specification of Letters Patent.

Patented Aug. 19, 1919.

Application filed February 26, 1919. Serial No. 279,310.

vent in most cases is simply to get the protectlve materlal on the surface to be treated, whereupon, by volatilization or oxidation of the solvent, the protective material dries into a film coating. In the case of wall board, the protective material, which dries into the film coating, must not only be moisture proof to a. very large extent, but must, in

provision of an improved size particularly adapted to be applied to wall board. While I have herein made particular reference to the use of the size for wall board, I wish it to be understood that the size may be extensively used for all purposes where a size of this character is suitable, and more particularly in connection with products made from wood fiber, wood pulp, and the like. The improved size of the present invention is a liquid at ordinary temperatures and consists of a compound or mixture of various substances in suitable proportions, which, when. applied under proper conditions to wall board, or other wood fiber products, satisfactorily fulfils the aforementioned requirements.

' The protective or film coating material of the improved size comprises a suitable resin, such as ordinary rosin, or the like, and a waxy substance, such, for example, as parafiin wax'l These materials are dissolved or cut in a suitable solvent to obtain the desired working consistency. At ordinary temperatures, the improved size is a thin liquid, comparable in body to a varnish.

The improved size of the invention may vary in composition, but for wall board of Wood pulp-fiber, as now ordinarily manufactured, a composition containing rosin,

wax and solvent in about the following proportions is satisfactory.

Rosin about 47% by weight Wax about 3 to 4% by weight Solvent about 48 to 49% by weight The wax may be a paraflin or its equivalent, and as a volatile solvent I prefer to use benzene or gasolene mixed with about an equal volume of kerosene. I use equal amounts by volume of kerosene and gasolene, in order to produce a cheap solvent. In place of this mixture, I may and often do use naphtha as the solvent, although the all-naphtha solvent is more expensive than the gasolene-kerosene solvent.

Slaked lime may be added to the size for hardening the rosin and for neutralizing the size of the following composition to give excellent results when applied to wall board:

Rosin about 47 Lime "about 1. 5% Paraffin wax about 3. 5% Kerosene; about 25 Gasolene about 23 The percentages of resin, wax and solvent or thinners may be varied through relatively wide limits, without departing from the spirit of the invention. Thus, the percentage of resin in the size may vary between and 60%, the percentage of wax between l% and 5% and the percentage of solvent between 40% and 60%.

The size may be applied to the board in any convenient way, as by running the board through a bath and allowing it to remain in the bath for a period of time sufficient to permit absorption of the desired quantity of size, after which it is passed through squeeze rolls where the excess liquid adhering to the surface is squeezed off. Other methods of applying the size may, of course, be resorted to in accordance with common practice.

The amount of paraflin or other wax admixed with the resin is dependent upon the degree of moisture proofness desired. Many sizing materials now in use close the surface and even waterproof, but fail to withstand the penetration of moisture. The proportions of resin and wax contemplated by the present invention are such as to give a well filled surface with a very high degree of moisture proofing. This moisture proofing characteristic of the size is imparted thereto by the wax. However, if too much wax is added the sized surface will be too greasy like comprising a composition made up for the proper application of painting or decorative agents. For this reason, the sizing compound should not contain over about 5% by weight of wax. A higher percenta e of Wax interferes with painting, and, in t e case of Wall board, this is objectionable, since it is usually desirable to decorate the Wall board panels.

As the result of its wax content, the improved size of the present invention possesses eXcellent moisture repellent properties. It should be noted, however, that the presence of the wax does not result in the production of an unpaintable sized surface. This is in large part due to the relatively small amount of wax employed, and also to the fact that the relatively greater proportion of resin renders the wax content hard, and thus counteracts its inherent greasy characteristic.

The size of the present invention has no injurious effect upon the wood fiber, and is of such transparency and color that the original appearance of the surface to which it is applied is little changed. The size dries readily and without the necessity of racking or air drying the articles treated, and furthermore enhances the ainting and decorating possibilities of the sized surface. The improved size is, moreover, of low cost, both as to price per gallon and cost per one thousand square feet of surface treated.

. What I claim is l. A size for wood fiber products and the like, consisting essentially of a resin, a wax and a solvent in about the proportions by weight of 40% to 60% resin, 1% to 5% wax, and 40% to 60% solvent.

2. A size for wood fiber products and the like containing a resin, a Wax and a solvent in about the proportions by weight of 47% resin, 3 to 4% wax and 48 to 49% solvent.

3. A "size for wood fiber products and th;

0 about 47% of a resin, about 1.5% lime, a out 3.5% of a wax and about 48% of a solvent.

4. A size for wood fiber products and the like, containing from about 40% to 60% by weight of a resin and from about 1% to 5% by weight of a wax.

In testimony whereof I aflix my signature.

BENJAMIN WILSON SIDWELL. 

